(1) Field of the Invention
The invention relates to a check valve device for a scroll machine, and more particularly to a safety apparatus which utilizes the in-flow pressure difference to control the operation of a valve member for preventing the scroll members of the scroll machine from impact damage caused by a possible transient reverse flow.
(2) Description of the Prior Art
A conventional scroll machine or a volute compressor in the art can be structured as shown in FIG. 1. The conventional scroll machine comprises mainly a shell 10, a separating member 14 inside the shell 10, a non-orbiting scroll member 24 installed below the separating member 14, an orbiting scroll member 30 to mesh with the non-orbiting scroll member 24, a frame 12 to rest the orbiting scroll member 30 and other necessary components. When the non-orbiting scroll member 24 meshes with the orbiting scroll member 30, a plurality of closed compression chambers 34 are separately formed for accommodating working media (either gas or fluid) between the non-orbiting scroll member 24 and the orbiting scroll member 30. In operation, a motor 3 located under the orbiting scroll member 30 is used to drive the orbiting scroll member 30 following an eccentric motion via a connecting rotary shaft 36, and those compression chambers 34, at the same time, move with the moving contact lines formed between the non-orbiting scroll member 24 and the engaged orbiting scroll member 30 in such a manner that the occupied volume of individual compression chamber 34 become less and less as it moves toward the center of the scroll member 24 or 30. Thereby, a compressing effect upon the working media confined in each compression chamber 34 can be formulated.
Inside the shell 10, the separating member 14 is used to define a high-pressure room 18 thereabove and a low-pressure room 20 therebelow. The only through conjunction between the high pressure room 18 and the low-pressure room 20 is structured by a neck 26 extruding from the center of the non-orbiting scroll member 24 into the high-pressure room 18. The neck 26 has an axle hole 22 and an offset hole 13 to form a through passage connecting the high-pressure room 18 and the compression chamber 34 of the low-pressure room 20, respectively. The forced flow, driven by the motor 3, from the low-pressure room 20 to the high-pressure room 18 is thus passed through the volume-reduced compression chambers 34, the offset hole 13, and the axle hole 22, and finally emitted to the high-pressure room 18.
In the case that the scroll machine faces a stop operation, the flow of the working media will be naturally reversed its direction due to the pressure difference formed between the high-pressure room 18 and the low-pressure room 20. The reverse flow will impact the compression chambers 34 through the axle hole 22 and the offset hole 13 so that the rotation of the orbiting scroll member 30 will be reverse. During the reversing, collision between the non-orbiting scroll member 24 and the orbiting scroll member 30 will be inevitable and generate a large-scale impact and noise. Such an impact and noise will eventually reduce the life time of the scroll members 24 and 30, as well as the life time of other relative components.
As exemplified by the disclosures in the U.S. Pat. Nos. 5,186,613, 4,759,696, 5,088,905, 4,904,165, and 5,451,148, various means are provided to reduce the collision between scroll members by blocking the working media flow between the high-pressure room 18 and the low-pressure room 20. However, all the means utilized by aforesaid disclosures require the modification of the original tooling to manufacture the scroll machine, which will increase the product cost substantially. It is also obvious that all the means of the aforesaid disclosures can not be applied directly to the scroll machine manufactured by the original tooling.
In addition, it is taught in the U.S. Pat. Nos. 4,759,696 and 4,904,165 that spring energy has been utilized to provide the retrieving force for blocking the flow. However, a long-term non-stop operation of the scroll machine will expedite the fatigue or degrading of the spring and thus cause problems in maintenance eventually.